Software Licenses

Hasitha Chandula
4 min readSep 8, 2020

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A software license is a document that provides legally binding guidelines for the use and distribution of software.

Software licenses typically provide end-users with the right to one or more copies of the software without violating copyrights. The license also defines the responsibilities of the parties entering into the license agreement and may impose restrictions on how the software can be used. Software licensing terms and conditions usually include fair use of the software, the limitations of liability, warranties, and disclaimers, and protections if the software or its use infringes on the intellectual property rights of others.

Software licenses typically are either proprietary, free or open-source, the distinguishing feature being the terms under which users may redistribute or copy the software for future development or use.

There are many different types of software licenses, and the penalties for license non-compliance can be harsh. If you reuse a component without following the obligations of its license, the licensor might sue, and you might be forced to publish your own source code. To protect your code and your organization, you need to understand these software licenses before using any code, including libraries and frameworks, you didn’t write yourself. See our list of the top open-source licenses and their potential legal risks.

What are the different types of software licenses?

Here are five types of common software license models you should know about. Four are examples of open source licenses (which allow you to reuse code to some extent), and one disallows any reuse whatsoever.

Public domain.

This is the most permissive type of software license. When software is in the public domain, anyone can modify and use the software without any restrictions. But you should always make sure it’s secure before adding it to your own codebase. Warning: Code that doesn’t have an explicit license is NOT automatically in the public domain. This includes code snippets you find on the internet.

Permissive.

Permissive License is also known as “Apache-style” or “BSD style.” They contain minimal requirements about how the software can be modified or redistributed. This type of software license is perhaps the most popular license used with free and open-source software. Aside from the Apache License and the BSD License, another common variant is the MIT License.

LGPL.

The GNU Lesser General Public License allows you to link to open source libraries in your software. If you simply compile or link an LGPL-licensed library with your own code, you can release your application under any license you want, even a proprietary license. But if you modify the library or copy parts of it into your code, you’ll have to release your application under similar terms as the LGPL.

Copyleft.

Copyleft licenses are also known as reciprocal licenses or restrictive licenses. The most well-known example of a copyleft or reciprocal license is the GPL. These licenses allow you to modify the licensed code and distribute new works based on it, as long as you distribute any new works or adaptations under the same software license. For example, a component’s license might say the work is free to use and distribute for personal use only. So any derivative you create would also be limited to personal use only. (A derivative is any new software you develop that contains the component.)

The catch here is that the users of your software would also have the right to modify the code. Therefore, you’d have to make your own source code available. But of course, exposing your source code may not be in your best interests.

Proprietary.

Of all types of software licenses, this is the most restrictive. The idea behind it is that all rights are reserved. It’s generally used for proprietary software where the work may not be modified or redistributed.

Examples of software licenses

  • Single-user license — The software is licensed for a single user and often a single computer.
  • Multi-user license — This license allows you to install a program onto multiple computers used by multiple users. Typically this may be a set number of users. For example, a five-user multi-user license allows up to five people to use the program.
  • Site license — A program can be installed on an unlimited amount of computers, as long as they’re at the location of the site license. Site licenses are usually for schools and businesses.

How do I know what licenses apply to the code in my codebase?

Before you can determine which licenses govern any reused code in your codebase, you need to create a software bill of materials or a list of all the components in your code. And the fastest way to generate that list is with a software composition analysis tool. A good SCA tool will be able to find full components as well as code snippets, and it’ll tell you which licenses apply to each piece of code and whether you might be using licenses that have conflicts.

Are software licenses transferrable?

In most situations, a retail version of an operating system license and software license is transferrable as long as it isn’t used on the older computer. For example, a retail version of Microsoft Windows can be transferred to another computer as long as the other computer is no longer used or switched its operating system

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Hasitha Chandula
Hasitha Chandula

Written by Hasitha Chandula

Senior Full Stack Engineer specializing in TypeScript & Go. I create scalable web apps, love learning new tech, and thrive on teamwork.

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